Glass ionomer cements in general are materials that comprise an ionic polymer composition and a reactive glass composition, where mixing these two compositions in an aqueous environment initiates a cement setting reaction. These materials are used in a number of applications in the dental and medical industries where a cement is used on, for example, tooth or bone structure. Conventionally, these materials are provided in two part systems, wherein one of the parts is in a powder form. Typically, the ionic polymer is provided in an aqueous liquid form and the reactive glass is provided as a powder. Considerable effort has been expended in designing systems to mix a powder and a liquid quickly and easily to enable complete reaction of conventional glass ionomer systems.
U.S. Pat. No. 4,288,355 to Anderson discloses surgical cement compositions comprising a concentrated non-gelling aqueous solution of a polycarboxylic acid and an aqueous suspension of metal oxide powder which when mixed together form a plastic mass which is formable into the desired shape before it hardens. These cements are formulated using a paste:paste format, but in all cases both pastes are aqueous pastes. This reference fails to disclose use of an organic paste for delivery of the reactive filler.
U.S. Pat. No. 4,591,384 to Akahane discloses dental cement compositions comprising a metal oxide and second ingredient capable of reacting with the metal oxide. The composition further comprises a tannic acid derivative that is sparingly soluble in water and a reducing agent that is soluble in water. Various forms of combining these two reactive ingredient are disclosed at column 2, lines 18-27. Included in this recitation is "powder/liquid, powder/paste, paste/paste, paste/liquid and the like," apparently indicating that all forms of delivery are equivalent for the cement system disclosed therein.
U.S. Pat. No. 5,063,257 to Akahane discloses dental glass ionomer cement compositions comprising (a) a polymer of an alpha-beta unsaturated carboxylic acid, (b) a fluoroaluminosilicate glass powder, (c) a polymerizable unsaturated organic compound, (d) a polymerization catalyst, (e) water, (f) a surfactant and (g) a reducing agent. Paste:paste compositions are exemplified having the ionomer in an aqueous paste and the reactive filler in an organic paste.
U.S. Pat. No. 5,154,762 to Mitra et. al discloses a Univeral Water-Based Medical and Dental Cement, wherein the cement contains water, acid-reactive filler, water-miscible acidic polymer, an ethylenically-unsaturated moiety, photoinitiator, water-soluble reducing agent and water-soluble oxidizing agent. Two-part paste:paste formulations are broadly disclosed at column 2, lines 58-66.